Kiln vs. Air Dry

Which do you prefer

  • Air Dried

    Votes: 11 23.9%
  • Kiln Dried

    Votes: 12 26.1%
  • Either of the 2 is fine by me

    Votes: 23 50.0%

  • Total voters
    46
Kiln dried is the more stable, Once it has been dried the wood may take in and expell some surface moisture as the weather or conditions change. Air dried is not totally dry and will constantly expell moisture content as it ages. (reason very old pieces fall apart ) the joints will loosen and open if the MC of the environment is not the same as the MC of the wood.

So, Good furniture is built from Kiln Dried wood. Air dried is OK for upholstered furniture but tight joints need a more stable wood. Kiln Dried is the more stable.
 
Kiln dried is the more stable, Once it has been dried the wood may take in and expell some surface moisture as the weather or conditions change. Air dried is not totally dry and will constantly expell moisture content as it ages. (reason very old pieces fall apart ) the joints will loosen and open if the MC of the environment is not the same as the MC of the wood.

So, Good furniture is built from Kiln Dried wood. Air dried is OK for upholstered furniture but tight joints need a more stable wood. Kiln Dried is the more stable.
Bill,
I hate to disagree with you but all wood will giveup and take on moisture as the humidiity changes. Wood wants to be in equalibrium with the environment. I have seen kiln drying change the color of some wood like walnut for instance. From my expierance restoring antiques 100% of the joint failure has been the fault of the glue that was used back then. I have worked on pieces well over 100 years old.
 
+2 for what Don said.

Air dried - when dried to the same MC - will be just as stable as kiln dried.

Air dried is better for steam bending, since it hasn't been 'tempered' by the kiln's heat.

If KD walnut is steamed during drying - to blend the colors - it becomes bland and muddy looking when compared to sir dried.
 
I voted for #3 cause I really don't know much about the diffferences.

I kinda knew about the stability of kiln dried - and about appearance of air dried.

I have some air dried Cherry - and it looks pretty good to me. I also have some air dried Walnut and that also looks great.

However - I do have two very untrained eyes.
 
Air dried always presents the possibility of infestations. Generally, the modern kilns reach high enough temps to kill bugs and larvae.
Also note that unless you live somewhere very dry, air drying will not get you down below 10%. If you build furniture that is air dried to 10 or 11% and move it into a heated and air conditioned home you have a higher probabilty of the wood continuing to dry and shrink and crack.
This is common when antiques are moved from the barn or garage into the home.
These points could be argued forever so this was just my take on it.
Would I personally buy air dried wood? No, for me the risk is too great.
 
Hm

I voted for air dried, but I end up using kiln dried most of the time. I don't get my hands on much air dried lumber. On the other hand, my turnings are usually air dried.

I am not so sure you need to live in a dry environment to get air dried lumber under 10%. Granted, I haven't dried wood that is stickered in large stacks, but the 1", 2", and 3" thick slabs I cut while blanking out turning stock get to 7-8%. It takes a while, that's for sure, but they're as dry as any kiln dried stock stored in a garage in Michigan.

Hutch
 
Bill,
I hate to disagree with you but all wood will giveup and take on moisture as the humidiity changes. Wood wants to be in equalibrium with the environment. I have seen kiln drying change the color of some wood like walnut for instance. From my expierance restoring antiques 100% of the joint failure has been the fault of the glue that was used back then. I have worked on pieces well over 100 years old.

You may disagree but you said the same thing. Wood will continue to dry over time according to the MC of the environment. when it has been kiln dried, it has a better chance of mating with the environment if kept in a snug home or ACed home.

As for the antique furniture we have a Chicken vs Egg situation. Did the glue fail because the joint pulled apart from shrinkage or the joint pulled apart because of glue failure? We'll never know. I have seen some very old pieces with very tight joints held together with very old glue... Why would one piece fail and not another? What are the variables? My house is full of 100-150+ years old pieces some with reglued joints and some in original condition with tight joints.

With the coloring situation, I don't believe that was in the original Query, and I agree that steaming takes the "Life" out of walnut.... But kiln drying is not steaming (although some plants do that in unison because it salvages more sellable wood from the rejected sap) But consider that Spalting will stop with kiln drying. Although Spalted pieces are an interesting beauty of their own, more often than not it is rejected as a flaw. The kiln solves that problem. Some woods, such as Holly have to be felled, sawn, and instantly kiln dried to prevent the white wood from turning blue (gray) due to the mold it hosts.

Again with the exchanging of moisture, Kiln dried wood reaches a more stable condition deep and throughout the thickness of the wood. In that process the open cells will close due to controlled shrinkage, this hinders the free exchange of moisture. Depending on how long wood is exposed to a moisture change the depth of the penitration or the expelling is slowed by the closed cells whilst the open cells of the Air Dried woods facilitate migration of moisture.

If need be, I'll climb up into the attic and find some old Textbooks that supports my statement. As best I remember from school (of course that was back in the dark ages) Those details were lectured into my Love struck brain... Or you can do some research based on fact rather than opinion.

Which is the best or better wood selection, It depends on how the piece is to be kept and what you plan to do. For most project pieces I prefer kiln dried as the conditions of prep are better maintained and I always seem to have less waste with kiln dried and less waste is a good thing with the costs of lumber ever increasing.
 
Air dried always presents the possibility of infestations. Generally, the modern kilns reach high enough temps to kill bugs and larvae. .

True, but air dried wood that's infested isn't all that common, and it can be treated with Borates if it is.

Also note that unless you live somewhere very dry, air drying will not get you down below 10%. If you build furniture that is air dried to 10 or 11% and move it into a heated and air conditioned home you have a higher probabilty of the wood continuing to dry and shrink and crack...

So, the humidity in my heated and air conditioned house seldom goes below 30%. How low does yours go? Maybe down to 10% if you live in the desert, but otherwise wetter.

I have some hundred year old furniture, joined with hide glue, that's still as solid as the day it was made, and it's been on the Virginia Coast, Seattle, WA, Southern California, and now Ohio, with no noticeable changes.
 
Unless you have a kiln in your back yard the lumber from a lumber yard that has been kiln dried will be the same MC as lumber that has been properly air dried.
Kilns in my part of the woods only dry to between 15 and 20% due to the fact that to go lower is a wast of resources. Once the wood is removed from the kiln it will immediately move to the moisture content of the air around it.
The big reason for kiln drying is to speed up the proses mills can't afford to have piles of lumber setting around for 2 or more years waiting for it to dry. It also reduces shipping cost (water is heavy). Get it cut into lumber and get it into the kiln and they end up with more sale able lumber. Not as much loss to staining that can be problem with air drying.
All in all at the end of the day if your lumber has been properly acclimated to it's end environment movement, splitting, cupping all are non issues.
As to what is better. Dry wood.:thumb:
 
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